Inoffirsoll-baira



May 12, 1931. F. w. PARSONS 1,804,892

CLEARANCE-VALVE ASSEMBLY Filed 001:. 22. 1927 INVENTOR. Ikedem'olc Wl'amoui Patented May 12, 1931 uurreo e -sisal FREDERICK W PARSONS, OF ELllEIRA, YORK, ASSIGNOR TO INGERSOLL-RAKD COMPANY, OFJ CITY, "NEXU J A CORPORATION OF NEW JERSEY.

CLEARANCE VALVE ASSEMBLY 1 Application filed. October 22, 1927. Serial No. 227,971.

This invention relates to fluid compressors, but more particularlyto a clearance valve for controlling the passage of fluid to clearance pockets provided at either end of the compressor cylinder, in order to regulate the load of a compressor at constant speed.

It is an object of thisinvention to produce a valve of simple construction, 'quietin its action and cheap to construct wherein the packing about the valve may beeasily adjusted from the outside of the compressor cylinder without removing any part ofthe;

Other objects will be in part obvious and in part pointed out hereinafter The drawing shows a vertical sectional view of the valve and part of the compressor cylinder to which the'valve is attached.

. Referring to the drawings, the innerand outer walls of a, compressor cylinder are,

shown at A and B respectively and these walls form clearance pockets .0 and D A.

threaded aperture E in the; outer wall B is aligned with a smaller openingF in the inn er wall A. Into the aperture E is screwed a valve guide G,'formed so as to have a shoulder H near its outer end and large and small bores J and K respectively. The bores J and K form a shoulder L at their meeting point. A hollow cylindrical piston valve 0 normally seats on a valve seat P and is reciprocable in the bore K in the valve guide G. The exterior or guiding surface 0 of the I valve 0 is of substantiall uniform diameter throughout the length of the valve, although, if desired, the unguided end ofthe valve may we slightly relieved. Packing Q isplaced around the upper cylindrical part B of the valve 0. 'This packing is held in place against the shoulder L by a hollow plug S which slidably fits the bore J. A spider T is seated at U on the valve guide and its arms V project outwardlyfroni the guide.

Bolts W are passed through the arms V and.

screwed into the outer cylinder walls B thus securing the spider T in place. A set screw X' having a lock nut Y is centrally located in the spider so that its end bears against the plug S in such a manner that by screwmg the set screw X downwardly the pack- ,valve guide G for preventing leakageot air to the different clearance pockets is controlled ing Q will be compressed and tightened around the valve stem surface R. A pipe Z threaded into the plug S at e is adapted to carry fluid pressure from source of supply (not shown) to the chain-j her 5 formed inside of the plug S. It will i be noted here that the area of the valve ex posed to I'GCGIVQI'VPTQSSUTG carried by the pipe Z is larger than the area of the valve exposed to cylinder pressure. At the outer edge of i the aperture E a recess 0 is formed so that a I ring of packing cl may be interposed between t the cylinder wall and the shoulder H of the at this point. 0

In the operation of the device the force exerted on the larger outer end of the valve I 0 tends to hold the valve onto its seat P,

against variable pressure upon the inner smaller pressure area and this variable pressure changes with the stroke of the compressor and tends to open the'valve. Bythis means the passage of fluid from the cylinder in accordance with the load of the compressor at constant compressor speed. I claim: r c A clearance valve assemblycomprising a cylindrical valve guide having a differed tial bore, a plug member slidable in the guide for closing said bore at its outer. end and having a chamber to receive pressure fluidfrom a source, an aperture for the admission I. of pressure fluid from an external source into 1 o the chamber, a cylindrical clearance valve FREDERICK w. masons; 

